Pleydell E J, Brown P E, Woodward M J, Davies R H, French N P
Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand.
Appl Environ Microbiol. 2007 Jan;73(1):203-10. doi: 10.1128/AEM.01482-06. Epub 2006 Nov 3.
Currently, there are limited published data for the population dynamics of antimicrobial-resistant commensal bacteria. This study was designed to evaluate both the proportions of the Escherichia coli populations that are resistant to ampicillin at the level of the individual chicken on commercial broiler farms and the feasibility of obtaining repeated measures of fecal E. coli concentrations. Short-term temporal variation in the concentration of fecal E. coli was investigated, and a preliminary assessment was made of potential factors involved in the shedding of high numbers of ampicillin-resistant E. coli by growing birds in the absence of the use of antimicrobial drugs. Multilevel linear regression modeling revealed that the largest component of random variation in log-transformed fecal E. coli concentrations was seen between sampling occasions for individual birds. The incorporation of fixed effects into the model demonstrated that the older, heavier birds in the study were significantly more likely (P = 0.0003) to shed higher numbers of ampicillin-resistant E. coli. This association between increasing weight and high shedding was not seen for the total fecal E. coli population (P = 0.71). This implies that, in the absence of the administration of antimicrobial drugs, the proportion of fecal E. coli that was resistant to ampicillin increased as the birds grew. This study has shown that it is possible to collect quantitative microbiological data on broiler farms and that such data could make valuable contributions to risk assessments concerning the transfer of resistant bacteria between animal and human populations.
目前，关于抗微生物药物耐药共生细菌种群动态的已发表数据有限。本研究旨在评估商业化肉鸡场中个体鸡的大肠杆菌种群对氨苄西林耐药的比例，以及获取粪便大肠杆菌浓度重复测量值的可行性。研究了粪便大肠杆菌浓度的短期时间变化，并在不使用抗菌药物的情况下，对生长中的鸡排出大量氨苄西林耐药大肠杆菌的潜在因素进行了初步评估。多级线性回归模型显示，个体鸡在不同采样时间之间，对数转换后的粪便大肠杆菌浓度随机变化的最大组成部分。将固定效应纳入模型表明，研究中年龄较大、体重较重的鸡排出更多氨苄西林耐药大肠杆菌的可能性显著更高（P = 0.0003）。对于总的粪便大肠杆菌种群，体重增加与高排泄量之间未观察到这种关联（P = 0.71）。这意味着，在不使用抗菌药物的情况下，随着鸡的生长，对氨苄西林耐药的粪便大肠杆菌比例增加。本研究表明，在肉鸡场收集定量微生物学数据是可行的，并且这些数据可为动物和人类种群之间耐药细菌转移的风险评估做出有价值的贡献。
